刀额新对虾人工繁殖技术研究

刀额新对虾(Martepenaeusensis),属十足类甲壳动物,壳薄体肥,肉嫩味美,是新对虾属中经济价值较高者。主要生活在亚热带海域中,我国浙江至北部湾和海南岛沿岸海域都有分布,是南海极为重要的经济虾类,水深20～50m,19～30℃的自然生长海区环境都是良好的虾场。其食性认捕食底栖生物为主兼食底层浮游生物及游泳生物,据胃含物分析,其食物组成种类复杂,胃中饵料种类有17个类群[1]。因其生长快、病害少等特点,养殖前景看好。目前广东[2]、福建(程家骅,1992)有少量人工种苗,上海市已立项进行专项研究,计划大规模推广。现将其人工繁殖技术总结如下。…     

刀额新对虾幼体的培育及特点

在水温26～28℃,pH8.1～8.3,海水盐度27.6～29.7的条件下,刀额新对虾幼体从无节幼体第一期(N_1)培育至仔虾幼体第一期(P_1),历时10d,成活率81.9%;至仔虾幼体第8～10天(P_(8～10)),成活率为80%。刀额新对虾幼体发育具有许多不同于其他对虾类幼体的发育特点,其糠虾期身体仅稍倾斜而不呈倒悬状态,极少摄食丰年虫无节幼体,直至P_(3～4)摄食丰年虫幼体现象才较多见。     

刀额新对虾染色体核型及细胞核DNA含量

以刀额新对虾胚胎、无节幼体、卵巢、精巢等为材料 ,空气干燥法制备染色体 ,并初步进行核型分析。结果表明 ,刀额新对虾的染色体数目为 2n=78,n =39,核型为 2n=78=40M 1 0SM 1 4ST 1 4T。以刀额新对虾血淋巴、卵巢、肌肉、鳃为材料 ,以鸡血细胞为DNA标准 (2 50pg/ 2c) ,使用PartecCCAⅡ型流式细胞仪测定了刀额新对虾细胞的基因组DNA含量 ,其值为鸡血细胞的 1 75倍 ,绝对含量为 4 375pg/ 2c。     

不同氧饱和度环境刀额新对虾幼体对微藻脂肪酸在沉积物中降解的影响研究

以中国近海典型赤潮藻中肋骨条藻(Skeletonema costatum)为研究对象,考察不同氧饱和度环境下底栖甲壳动物对有机物在沉积物中降解的影响。通过对比不同氧饱和度培养模拟体系中中肋骨条藻在有/无刀额新对虾(Metapenaeus ensis)幼体活动背景下的降解过程,追踪中肋骨条藻中4种主要脂肪酸(C14:0,C16:0,C16:1(7)和C20:5)在100%,50%,25%和0%的氧饱和度体系中的降解行为。结果表明,100%氧饱和度体系中刀额新对虾幼体的活动能明显加快脂肪酸在沉积物中的降解(约为对照组的1.2~1.7倍),特别是对饱和脂肪酸C14:0和C16:0的作用最为明显;而在50%氧饱和度的缺氧体系中,在前三天的培养中,刀额新对虾幼体的活动逐渐减弱直至最终死亡,死亡之前的扰动增加了有机物在次表层沉积物中的埋藏并降低了其降解速率。研究还发现,在100%氧饱和度体系中,刀额新对虾幼体的扰动作用促进大量脂肪酸转移到次表层沉积物和悬浮颗粒中;而在50%氧饱和度体系中,这种转移作用明显变小。对于氧饱和度25%和0%的环境,刀额新对虾幼体在模拟培养开始后迅速死亡,对有机物质降解几乎没有影响。     

基于裤式拖网法的虾拖网网囊网目选择性试验与分析

为研究虾拖网网囊网目对主要渔获种类的选择性,于2017年9月在南海区采用裤式拖网法进行选择性试验。在SELECT模型框架下,使用极似然估算法,结合单网次和联合网次的数据,同时考虑网次间差异,估算网囊对主要渔获种类的平均选择性。共完成14网次作业,其中对照网囊之间的渔获性能比较试验4次,试验网囊的选择性试验10次。研究表明:对照网囊的位置对其渔获性能无显著影响;试验网囊对刀额新对虾(Metapenaeus ensis)的网次50%选择体长(L 50)为78.84~92.09 mm,平均为82.38 mm,网次选择范围(SR)为5.01~11.32 mm,平均为6.39 mm,网次相对作业强度(p)为0.44~0.71,平均为0.52;试验网囊对黄斑蓝子鱼(Siganus oramin)的网次L 50为59.20~76.80 mm,平均为71.17 mm,网次SR为5.30~16.87 mm,平均为14.20 mm,网次p为0.43~0.71,平均为0.63。试验网囊对刀额新对虾的网次和平均L 50值均大于其首次性成熟体长(80 mm),可见试验网囊对刀额新对虾的资源利用是合理的。本试验的裤式拖网法和数据处理方法可为今后拖网选择性研究提供参考。     

虾池养殖环境有机污染物降解细菌的筛选

在实验室条件下通过富集培养共分离出 1 2 1株菌进行筛选。利用需氧性、BOD2 / COD0 、胞外酶等指标进行筛选 ,最后筛选到 7株对富营养有机物具有较高降解能力的细菌 ,它们均能产生酪蛋白酶、明胶酶、脂酶 (Tween- 80 )、淀粉酶其中 4株细菌还能产生卵磷脂酶。通过测定 BOD5及 COD来衡量 7株细菌利用对虾饵料的能力 ,5d内对虾饵料培养基的 CODMn去除率达到 59.6%～ 79.2 %。用常规生理生化方法将细菌鉴定到属 ,其中 1株为弧菌属细菌 (Vibrio spp.) ,6株为芽孢杆菌属细菌(Bacillusspp.)。     

中国对虾家系幼体对氨氮和pH值的耐受性比较

采用人工授精技术建立中国对虾家系,对建立的20个家系幼体通过急性毒性试验进行抗氨氮和pH值性状的比较.结果表明:不同试验时间中国对虾家系对氨氮和pH值的耐受性差异极显著(P<0.01)和显著(P<0.05),24,48和72 h对氨氮耐受性的平均半数致死值分别为62.15,30.31和15.60 mg/L,对pH值耐受性的平均半数致死值分别为9.99,9.41和9.12.以平均LD50值为评价指标,综合24,48和72 h各家系对氨氮和pH的耐受性,最终筛选出对氨氮耐受性最强的家系8个,对pH值耐受性最强的家系10个,对氨氮和pH值耐受性均较强的家系7个,为构建中国对虾抗逆基础群体,开展中国对虾抗逆新品系的选育工作提供了基础.     

Experimental Studies on Extraction of Modified Suction Caisson (MSC) in Sand by Reverse Pumping Water

A suction caisson can be extracted by applying reverse pumping water,which cannot be regarded as the reverse process of installation because of the dramatically different soil?structure interaction behavior.Model tests were first carried out in this study to investigate the extraction behavior of the modified suction caisson(MSC)and the regular suction caisson(RSC)in sand by reverse pumping water.The effects of the installation ways(suction-assisted or jacking installation)and the reverse pumping rate on the variations of the over-pressure resulting form reverse pumping water were investigated.It was found that neither the RSC nor the MSC can be fully extracted from sand.When the maximum extraction displacement is obtained,the hydraulic gradient of the sand in the suction caisson reaches the critical value,leading to seepage failure.In addition,the maximum extraction displacement decreases with the increasing reverse pumping rate.Under the same reverse pumping rate,the final extraction displacements for the RSC and MSC installed by suction are lower than those for the RSC and MSC installed by jacking.The final extraction displacement of MSC is almost equal to that of the RSC with the same internal compartment length.Based on the force equilibrium,a method of estimating the maximum extraction displacement is proposed.It has been proved that the proposed method can rationally predict the maximum extraction displacement and the corresponding over-pressure.     

钩虾和蜾蠃蜚群落在日本对虾养殖池塘中变动规律的研究

2009年4～7月,对移入日本对虾养殖池的钩虾和蜾蠃蜚群落进行了研究.共调查到2种钩虾,3种蜾蠃蜚.钩虾的优势种为中华原钩虾;蜾蠃蜚的优势种具有明显的交替性,放养后前53 d,优势种为大蜾蠃蜚,78 d后,优势种为隐居蜾羸蜚.钩虾群落的物种多样性(H')与均匀度(J)在放养当天达到最高,放养后第67天出现差异显著;蜾蠃蜚群落的物种多样性(H')与均匀度(J)在放养后第64天最高,第90天出现差异显著.钩虾的生物量和丰度放养后第30天达到最大值,随后快速下降;蜾蠃蜚的生物量和丰度放养后第14天达到最大值,其丰度在第64天达到第二个高峰.同时,钩虾和蜾蠃蜚群落不同体长个体的丰度百分比差异明显,表现出一定的周期性变化规律.由此,初步分析了引起群落变化的两类原因,提出了钩虾和蜾蠃蜚群落结构的调控方案.     

陆架沙丘(波)形成发育的环境条件

陆架大、中、小、巨沙丘(沙波)发育的动力机制与河流沙波有相似之处,也有许多差异,前者含定时多向的潮流、持续定向的洋流和偶发性的暴风浪流,后者为单向持续水流。20～100cm／s的底流速是发育沙丘的动力因素,水流的多向性和浪流的偶发性又常常制约沙丘发育的强度和迁移的速度;陆架浅水区(小于18m)受破浪的影响,沙丘尺度与水深呈微弱负相关,深水区水深的影响甚微。陆架输沙量是沙丘发育的物质条件,特别是细、中砂底质,在此粒度范围内沙波尺度与粒径呈微弱正相关,平缓广阔的地形在沙丘发育中也起一定的作用。     

Stock Identification of Chum Salmon (<Emphasis Type="Italic">Oncorhynchus keta</Emphasis>) Using Trace Elements in Otoliths

The relationship between trace elements in chum salmon otoliths and in their rearing water was investigated to develop ways to distinguish chum salmon stocks in Korea. Rearing water and otoliths of hatchery-reared chum salmon fry were collected from three major hatcheries (Yangyang, Samchuk, and Uljin) on the east coast of Korea in spring 2001 and 2002. Trace elements in the otoliths and rearing water were analyzed using inductively coupled plasma mass spectrometry (ICP-MS) at the Korea Basic Science Institute. The chemical composition of rearing water and otoliths of the salmon fry at specific sites did not vary significantly through the study period. The ratios of some trace elements to Ca in rearing water, such as Sr/Ca and Ba/Ca, was clearly reflected in the chemical composition of otoliths, although the absolute concentrations were different. These two elements may be useful in distinguishing between salmon hatcheries, which have different chemical environments. Discriminant analysis with the ratios of eight elements to Ca (Na/Ca, Mg/Ca, Al/Ca, Cu/Ca, Sr/Ca, Ba/ Ca, Mn/Ca, and Zn/Ca) revealed a distinct separation of natal area in stocks. The analysis of otolith chemistry may be an effective technique for identifying the origins of wild salmon caught at sea.     

Distribution of Scyllarid Phyllosoma Larvae (Crustacea: Decapoda: Scyllaridae) in the Kuroshio Subgyre

Using ichthyoplankton samples collected in the Kuroshio Subgyre during early summer cruises, we examined spatial distributions of scyllarid phyllosoma larvae in the Subgyre, particularly of the genus Scyllarus. The present study has two objectives: (1) to reveal species composition of Scyllarus phyllosoma larvae in the Kuroshio Subgyre, and (2) to examine larval recruitment of Scyllarus species as contrasted with that of Panulirus, particularly P. japonicus, the larval recruitment of which has been examined in detail. A total of 218 phyllosoma larvae collected in the present study belonged to two families (Palinuridae and Scyllaridae) representing 5 genera and 11 species. Phyllosoma larvae of two Scyllarus species (S. cultrifer and Scyllarus sp. c) were abundant among the collected larvae, and were found mainly in the following three regions located within the Kuroshio-Counter Current region south of Kuroshio Current: the water east of Okinawa Is., the water far east of Okinawa Is. (or far south of Shikoku Is.), and the water around Hachijojima Is. Larvae of each of the above two Scyllarus species collected in the three regions may belong to different populations: larvae collected in the water around Hachijojima Is. may come from their benthic populations along the Pacific coast of Honshu and Shikoku Is., central Japan, while larvae collected in the other two regions may come from their benthic populations of the Ryukyu Archipelago and Taiwan. Judging from their shorter larval period and current systems within the Kuroshio Subgyre, these Scyllarus larvae may be destined for death. An erratum to this article is available at .     

Identification of the multidrug resistance-associated protein (mrp) related gene in red mullet (Mullus barbatus)

Multixenobiotic resistance mechanism (MXR) in aquatic organisms is mediated by the activity of the P-glycoprotein (Pgp) transporter that binds and actively effluxes different chemicals out of cell. In addition to the Pgp, several other, non-Pgp transport proteins have been recently identified in different human and animal tissues. Given their characteristics and tissue distribution we hypothesized that members of the so-called multidrug resistance-associated protein (MRP) family may be expressed in aquatic organisms. This study attempted to identify MRP related genes in different tissues of several marine and freshwater bivalves (Mytilus galloprovincialis, Dreissena polymorpha, Anodonta cygnea) and fish species (Mullus barbatus, Cyprinus carpio, Salmo trutta). Following an alignment of known MRP1 and MRP2 human sequences, as well as the GenBank available mrp2 sequences from different animals, we determined highly conserved regions and used them to design three pairs of consensus primers. Total RNA was isolated, reverse transcribed to cDNA and the obtained cDNAs were PCR amplified with the corresponding primers. The amplified PCR products were sequenced and their homology compared with Pgp and MRP protein sequences from different species. The expression of MRP related mRNA was clearly identified only in liver tissue isolated from red mullet, with homologies at the protein level ranging from 75% to 76%. Described results clearly pointed at the possibility that at least in the red mullet MXR as a general defense mechanism may be mediated by the activities of at least two different types of transport proteins.